Recording/playback systems for magnetic medium are subject to degradation during use as a result of the accumulation of debris which occurs on the magnetic transducer head(s) of such systems. Transducer heads include magnetic read/write heads and associated read/write elements. For example, in high-performance magnetic tape recording devices, magnetic tape usually contacts the magnetic transducer head. High contact pressures are generated during operation between the magnetic tape and the transducer head which strips surface contamination and weakly-attached particles from the magnetic tape. This debris accumulates on the magnetic transducer head which causes spacing loss between the read/write elements and the tape magnetic recording layer. Spacing loss can result from slots within the magnetic head being filled with debris, which renders the slots no longer effective. Spacing loss can also result from piles of debris accumulating over the transducer head, which physically causes the tape to lift off of the head.
A number of different techniques have been developed to clean clogged transducer heads. Typically, a scrubber is employed in some manner to physically remove debris from the transducer head. Hence, there is a need to periodically clean the magnetic transducer head(s). Accordingly, there exist several techniques for cleaning a magnetic transducer head.
According to one prior art technique, a separate, dedicated "cleaning cartridge" is used to perform periodic cleaning of the recording transducer head by scrubbing the transducer head. A "cleaning cartridge" contains a supply of unrecorded abrasive tape, the cleaning cartridge being inserted into a hard drive and the abrasive tape being drawn across the transducer head to clean the head. Such cartridge can be used to clean one or more magnetic transducer heads. For example, the recording heads found on a tape drive can be cleaned with a "cleaning cartridge". In order to utilize a "cleaning cartridge", the recording/playback of the medium must be stopped, with the data cartridge being removed, and the cleaning cartridge being inserted. The "cleaning cartridge" is then run within the record/playback system so as to clean the recording transducer. Once cleaning is complete, the "cleaning cartridge" is removed, and a data cartridge is reinserted. Such implementation is inconvenient because backup cannot occur without the attendance of personnel to insert the cleaning cartridge and data cartridges. Furthermore, after the "cleaning cartridge" has been used, a new data cartridge must be loaded into the system in order to evaluate the performance of the magnetic transducer head so as to confirm that cleaning has been successfully completed.
Where the magnetic recording/playback system is a tape recording/playback system, the cleaning cartridge includes an abrasive cleaning tape that can cause excessive tape head wear. The abrasiveness of the cleaning tape can be adjusted in order to tailor its effectiveness. If the cleaning tape is made sufficiently effective to thoroughly remove debris from the read/write heads, then the cleaning tape should only be used when it is necessary; otherwise, excessive head wear will result. Such a problem can occur where a piece of abrasive cleaning tape is provided as a leader on a data tape cartridge such that each time a tape is used the leader is used to clean a read/write head.
According to another prior art technique, a cleaning device includes a mechanism containing a brush or pad that is configured to scrub the transducer head in order to remove contamination. However, such cleaning device mechanisms add complexity, cost and constraints to a tape drive. For example, extra levers, cams, springs, gears and connections can fail, thus impacting tape drive reliability. Similarly, extra motors are costly, and require power, wiring, control instructions, and space. Furthermore, many such cleaners can only operate when the cartridge is loaded, thus limiting the frequency with which cleaning can be performed and the length of cleaning time.
Where magnetic tape is used to store computer data, the presence of errors represents a significant problem even if the errors occur infrequently. In certain applications, the loss of data requires that a user be able to perform a cleaning operation in response to recognized drop-out errors, but does not immediately prevent use of the equipment prior to cleaning. In some cases, the loss of a single bit of computer data can be of significant importance, and recovery from such an error must be done in a manner that ensures error-free data storage and retrieval. While error correction is possible via error correction algorithms, data loss can still present problems to a user.
One form of magnetic storage comprises existing linear tape drives that are used for storage and retrieval of computer data. Such tape drives use a single reel in the form of a magnetic tape cartridge to house the magnetic tape media. A special leader or leader block is attached to the magnetic tape media at one end which enables the tape drive to extract the magnetic tape from the magnetic tape cartridge. "Leader tape" is typically constructed of a piece of thicker, stronger tape that is sometimes used between the magnetic storage tape and the hub reel. Leader tape has been used to perform various functions, including identification, timing and an ability to resist wear. Leader tape can be located anywhere along a segment of tape, although it is typically found at the ends of a reel of tape. Accordingly, the leader can form a "leader tape" at the leading end of a tape reel, or a "trailer tape" at a trailing end of a supply reel. For purposes of this disclosure, "leader tape" will be used to refer to placement of such a tape at either end of a magnetic tape media.
"Tape recorder" is intended to refer to one form of magnetic recording/playback system comprising magnetic tape transcription equipment.
Such equipment is understood to include standard tape recorders having fixed or movable heads, as well as arcuate scan and helical scan transcription equipment as is typically used in analog and digital tape recorders. According to one implementation, a linear transcription head is employed, although such invention has application in other tape recording environments. As described here, "transcription" is intended to mean read and/or write operations that are performed with a tape recorder, and is not intended to be limited to a particular use or format for data.
Another prior art magnetic tape recording/playback system includes music cassette tapes that are often configured to include special material presented on a leader tape. Such music cassette tapes are configured with leader tapes that are presented over a head at the beginning sequence of operating the tape. Such leader tapes have been provided with a limited amount of abrasive cleaner. However, if the leader tape is provided with an abrasive cleaner having sufficient strength for cleaning a tape head, the leader tape will tend to cause undue wear to the tape head. Such undue wear results because each use of the tape is not selective and will cause abrasive cleaning, whether it is necessary or not. Therefore, end-of-tape abrasive leaders have limited application in that the abrasiveness, or cleaning effectiveness, must be reduced so that excessive wear does not occur to the tape head. Furthermore, there is no capability for determining whether a head needs to be cleaned, or whether or not a head has been sufficiently cleaned.
It is therefore desirable to employ a tape drive cleaning device that is simple, consumes little space, requires no additional motors or mechanisms, and can be operated at any time with no operator intervention. It is further desirable to implement such device so that it is relatively simple, economical, easy to monitor and repair, and more reliable in operation.